全新java初学者实践教程6(Java SE5.0版)
P:S .~Jq 基本语法3
"Y.tht H XW H5d-
8%mu8l 我们这个教程侧重的是实践的内容和语言的重点。在[font="Times]java语言中还有很多细节的东西,请参考[font="Times]sun公司的官方培训教程。我们这里不能一一讲述。这节课我们来给大家提供一些程序流程控制的一些例子供大家学习。计算机怎么做事情,是我们教给他的。我们用它解决实际生活中的问题,所以计算机要描述现实生活中的流程。[font="Times]Java语言中提供了[font="Times]4类程序控制语句,来描述流程:
P5V}#;v /HEw-M9z [font="Times] 1.循环语句[font="Times]:while,do-while,for
(/YHk`v2 Es`Px_k [font="Times]2.分支语句[font="Times]:if-else,switch,
2qNt,;DQ [font="Times]
j_[tu!~ 3.跳转语句[font="Times] break,continue,label: 和[font="Times]return
**0~K" ;\ [font="Times]
X`/k)N>l 4.异常处理语句[font="Times]:try-catch-finally,throw
tjS@meT zk+9'r`-D 实践:
@bLy,Xr& [font="Times] 1.循环语句
pF >i-i [font="Times] while 语句
I,DS@SK [font="Times]class While {
v~C
Czg [font="Times]public static void main(String args[]) {
FxY}m [font="Times]int n = 10;
@4C% +- [font="Times]while(n > 0) {
G_tCmu\ [font="Times]System.out.println("tick " + n);
Qljpx?E [font="Times]n--;
fbvL7*
( [font="Times]}
aO[w/cGQ [font="Times]}
1.hyCTnI [font="Times]}
hfB%`x#akQ [font="Times] do…while 语句
;;t yoh~t [font="Times] class DoWhile {
hZ,_6mNg [font="Times]public static void main(String args[]) {
BOX2O.Pm [font="Times]int n = 10;
MjRHA^b [font="Times]do {
Q{>k1$fkV [font="Times]System.out.println("tick " + n);
,qwuLBW [font="Times]n--;
9=tIz [font="Times]} while(n > 0);
IP pN@ [font="Times]}
>R_&Ouh: [font="Times]}
1I6px$^E\ 二者区别,[font="Times]do…while至少循环一次,而[font="Times]while的表达式要是为[font="Times]flase的话可以一次也不循环。再通俗一点,[font="Times]do…while就算是括号里的是[font="Times]flase,人家最少也能[font="Times]do一次。
TX/Xt7#R: [font="Times] for语句
Jpq~ [font="Times] class ForTick {
djZqc5t [font="Times]public static void main(String args[]) {
T>Z<]s [font="Times]int n;
8,%^
M9zBP [font="Times]for(n=10; n>0; n--)
wlvgg [font="Times]System.out.println("tick " + n);
P+sW[: [font="Times]}
[|L<_.8 [font="Times]}
'LC1(V!_j 与上面那两个的区别,[font="Times]for循环执行的次数是可以在执行之前确定的。通俗一点说吧,看这个例子[font="Times] for(n=10; n>0; n--)就是在括号里的时候,就已经知道要循环[font="Times]10次了。
-2[a2^a' 还有啊,[font="Times]for循环的部分可以为空的
u=s p`%? [font="Times]class ForVar {
:cECRm* [font="Times]public static void main(String args[]) {
EZGIf/ 3 [font="Times]int i;
33q}CzK [font="Times]boolean done = false;
=nS3p6>rZ [font="Times]i = 0;
6 "sSo j [font="Times]for( ; !done; ) {
x,-75 [font="Times]System.out.println("i is " + i);
"S]TP$O D [font="Times]if(i == 10) done = true;
6gE7e|+ [font="Times]i++;
?l )[7LR4 [font="Times]}
T^KKy0ZGM [font="Times]}
GxxW&y [font="Times]}
循环语句的例子下载 2zb"MEOS5 [font="Times] 2.分支语句[font="Times]
xp{tw$ [font="Times] if/else语句
)10+@d [font="Times]class IfElse {
W!(zT6# [font="Times]public static void main(String args[]) {
?`ZUR&
20 [font="Times]int month = 4; // April
HV|,}Wks6s [font="Times]String season;
F41=b4/ [font="Times]if(month == 12 || month == 1 || month == 2)
pnOAs&QAm [font="Times]season = "Winter";
eauF~md, [font="Times]else if(month == 3 || month == 4 || month == 5)
t{96p77)= [font="Times]season = "Spring";
@9s$4DS [font="Times]else if(month == 6 || month == 7 || month == 8)
Q2gq}c~ [font="Times]season = "Summer";
c@7rqHU-0 [font="Times]else if(month == 9 || month == 10 || month == 11)
HZge!Yp< [font="Times]season = "Autumn";
C'x&Py/# [font="Times]else
e"<OELA [font="Times]season = "Bogus Month";
Nf\LN$ &8 [font="Times]System.out.println("April is in the " + season + ".");
0(HU}I [font="Times]}
sgFEK[w.y [font="Times]}
]a`$LW} [font="Times]//这段程序输出[font="Times]:
(9a^$C* [font="Times]//April is in the Spring.
g7H(PF? [font="Times]// 注意[font="Times] “[font="Times]||”是或运算
<5051UEu [font="Times] switch语句
;V!D:5U [font="Times] class Switch {
|6-nbj [font="Times]public static void main(String args[]) {
AK4t\D)K1 [font="Times]int month = 4;
W=?<<dVYD [font="Times]String season;
Z`i(qCAd( [font="Times]switch (month) {
6gDN`e,@ [font="Times]case 12:
W>r+h-kR [font="Times]case 1:
E1
2uZ$X [font="Times]case 2:
,P0) 6> [font="Times]season = "Winter";
'&b+R`g' [font="Times]break;
ccxNbU [font="Times]case 3:
3v-~K)hl? [font="Times]case 4:
+}AI@+
[font="Times]case 5:
(ZlU^Gw#UB [font="Times]season = "Spring";
#'`{Qv0,
[font="Times]break;
R=?[Nz [font="Times]case 6:
Mtx 4'WZ [font="Times]case 7:
y~V(aih}D [font="Times]case 8:
8Zdn, }Z [font="Times]season = "Summer";
DlJo^|5 [font="Times]break;
;tf=gdX; [font="Times]case 9:
er\|i. Y [font="Times]case 10:
|.dRily+ [font="Times]case 11:
(8OsGn [font="Times]season = "Autumn";
4,ag(^}= [font="Times]break;
/-s6<e! [font="Times]default:
zQ PQ [font="Times]season = "Bogus Month";
=_^X3z0 [font="Times]}
5)40/cBe [font="Times]System.out.println("April is in the " + season + ".");
k5)om;.w [font="Times]}
rm_Nn8p, [font="Times]}
分支语句代码下载 wd6owr K sCyFp [font="Times]switch语句适合于条件非常多的逻辑
l^}c! 请看上述语句可以混合使用,请看
下载例子